Method and apparatus for processing a substrate

ABSTRACT

A method for processing a substrate includes a step of providing a substrate and a first step. In the step of providing a substrate, a substrate having a first film and a second film formed on the first film and having a pattern formed thereon is provided. In the first step, a protective film is formed on a side wall of the first film by a product generated by sputtering of the second film while a first processing gas is turned into plasma and the first film is etched simultaneously with the sputtering of the second film.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is based on and claims priority from Japanese PatentApplication No. 2019-122068 filed on Jun. 28, 2019 with the Japan PatentOffice, the disclosure of which is incorporated herein in its entiretyby reference.

FIELD

The present disclosure relates to a method and an apparatus forprocessing a substrate.

BACKGROUND

Conventionally, plasma etching is used in forming a cylinder hole, acontact hole, or other structure in manufacturing a semiconductordevice. In recent years, a shape abnormality such as bowing in a highaspect ratio contact (HARC) hole has been an issue.

According to one technique, for example, on a substrate, an organicfilm, a silicon-containing film, and a patterned mask may be formed inthis order from below. Then, a recess may be formed in the organic film.Then, a protective film may be formed on an inner wall surface of therecess by sputtering the silicon-containing film (see, for example,JP-A-2009-49141).

SUMMARY

The disclosure is directed towards a technique for controlling a shapeof a pattern formed by etching on a substrate.

According to an aspect of the embodiment, a method for processing asubstrate is provided, including providing a substrate including a firstfilm and a second film formed on the first film and having an openingformed in the second film, and turning a first processing gas intoplasma to etch the first film and to form a protective film on asidewall of the first film by sputtering of the second film.

According to the embodiment, it is possible to control the shape of apattern formed on the substrate by etching.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a flowchart of an exemplary method for processing a substrateaccording to one embodiment;

FIG. 2 describes an exemplary structure processed by a method forprocessing a substrate according to one embodiment;

FIG. 3 describes a step of forming a protective film in accordance witha method for processing a substrate according to one embodiment;

FIG. 4 describes a step of etching in accordance with a method forprocessing a substrate of one embodiment;

FIG. 5A describes a step for building up a mask in accordance with amethod for processing a substrate of one embodiment;

FIG. 5B further describes a step for building up a mask in accordancewith a method for processing a substrate of one embodiment;

FIG. 6A describes a step for preventing clogging in accordance with amethod for processing a substrate of one embodiment;

FIG. 6B further describes a step for preventing clogging in accordancewith a method for processing a substrate of one embodiment;

FIG. 7A shows exemplary structures for explaining the flow of FIG. 1;

FIG. 7B shows another exemplary structure for explaining the flow ofFIG. 1;

FIG. 8 is a flowchart of exemplary cycle 1 of a method for processing asubstrate according to one embodiment;

FIG. 9 is a flowchart of exemplary cycle 2 of a method for processing asubstrate according to one embodiment;

FIG. 10 is a flowchart of exemplary cycle 3 of a method for processing asubstrate according to one embodiment;

FIG. 11 is a flowchart of a combination of exemplary cycles of a methodfor processing a substrate according to one embodiment;

FIG. 12 is a diagram for explaining effects obtained by the method forprocessing a substrate according to one embodiment;

FIG. 13 shows exemplary structures for explaining conditions fordetermining whether or not to perform a process step in a method forprocessing a substrate according to one embodiment;

FIG. 14 illustrates an exemplary configuration of an apparatus forprocessing a substrate according to one embodiment;

FIG. 15A describes a structure formed in a process of manufacturing asemiconductor device;

FIG. 15B describes a pattern formed in a photoresist in a process ofmanufacturing a semiconductor device;

FIG. 15C describes a pattern formed in a silicon-containing film in aprocess of manufacturing a semiconductor device; and

FIG. 15D describes a pattern formed in a mask in a process ofmanufacturing a semiconductor device.

DESCRIPTION OF EMBODIMENTS

Hereinafter, various embodiments will be described in detail withreference to the drawings. The present embodiments are not intended tobe limiting. Further, respective embodiments can be appropriatelycombined as far as the combination is consistent with the disclosure.

Example of a Shape Abnormality Occurring in a Process of Manufacturing aSemiconductor Device

Prior to describing the embodiment, a shape abnormality occurring in aprocess of manufacturing a semiconductor device will be described. FIG.15A shows a structure formed in manufacturing a semiconductor device.FIGS. 15B, 15C, and 15D respectively show a pattern formed in aphotoresist, a pattern formed in a silicon-containing film, and apattern formed in a mask.

FIG. 15A shows a structure including an insulating film 11, an organicfilm 12 that is to be etched, a silicon-containing film 13, and aphotoresist (PR) 14 in this order from below. In the example shown inFIG. 15A, the insulating film 11 is, for example, a silicon oxide (SiO2)film, a silicon nitride (SiN) film, a silicon oxynitride (SiON) film ora silicon carbon-nitride (SiCN). The insulating film 11 may include astack of SiO2 and SiN, a stack of SiO2 and polycrystalline silicon(Poly-Si), or a stack of SiO2 and SiON. The organic film 12 is, forexample, a film containing carbon as a main component. The organic film12 is, for example, an amorphous carbon film (ACL: Amorphous CarbonLayer). The silicon-containing film 13 is an inorganic film containingsilicon as a main component. The silicon-containing film 13 is, forexample, a SiO2 film, a SiN film, a SiON film, a Poly-Si film, or SiCNfilm. The silicon-containing film 13 may be formed of such a materialthat it functions as an anti-reflection film (Arc: Anti-ReflectionCoating) in a lithography process.

After the structure shown in FIG. 15A is provided, the photoresist 14 ispatterned by photolithography as shown in FIG. 15B. The photoresist 14may be subject to EUVL (Extreme Ultraviolet Lithography). Subsequently,an etching gas such as CF4 is turned into plasma to etch thesilicon-containing film 13. The silicon-containing film 13 is removed(etched) along the photoresist pattern 14, so that thesilicon-containing film 13 is patterned as shown in FIG. 15C.Furthermore, O2 gas, H2 gas, N2 gas, or a mixed gas containing H2 gasand N2 gas, or the like is turned into plasma and the organic film 12 isetched through the patterned silicon-containing film 13. The organicfilm 12 is patterned to form a mask shown in FIG. 15D. The patternedorganic film 12 functions as a mask when the insulating film 11 belowthe organic film 12 is etched.

The organic film 12 is isotropically etched by oxygen radicals, and abowing 20, i.e., a side-etched portion in a vertical section of the maskpattern, is formed as shown in FIG. 15D. When the insulating film 11 isetched through the mask pattern with the bowing 20, the shape of theorganic film 12 is transferred to the insulating film 11, and the shapeof a hole formed in the insulating film 11 is deformed.

Embodiment

In the embodiment described below, when the organic film is etched usingthe silicon-containing film as a hard mask, a product (deposit)generated by sputtering the silicon-containing film forms a protectivefilm for reducing side etch of the organic film. In a method forprocessing a substrate according to a first embodiment, the area wherethe protective film is formed is, for example, an area of an aspectratio of at least 5 within a pattern (recess) in the organic film on thesubstrate; more specifically the protective film is formed in an area ofan aspect ratio of 5 to 7 within the pattern (recess) in the organicfilm. Further, in the method for processing a substrate according to thefirst embodiment, the shape of the pattern formed on a substrate byetching is controlled by combining a plurality of process steps. In oneof the steps, product formed through sputtering realizes the protectionof side walls of the pattern.

In the method for processing a substrate according to one embodiment, astructure S (see FIG. 2) having an insulating film 31, an organic film32, and a silicon-containing film 33 stacked in this order on asubstrate is processed. In the process, the organic film 32 is patternedto form a mask for etching the insulating film 31. FIG. 2 describes anexemplary structure processed by the method for processing a substrateaccording to one embodiment.

The insulating film 31 is, for example, a SiO2 film. The insulating film31 is etched through the patterned organic film 32 to form apredetermined pattern. The pattern formed in the insulating film 31 maybe a cylinder hole, a contact hole, and the like of a semiconductordevice.

The organic film 32 is, for example, a film primarily containing carbon.The organic film 32 is, for example, an amorphous carbon film. Themethod for processing a substrate according to the present embodimentcontrols mainly the shape formed through the etching in the organic film32.

The silicon-containing film 33 is, for example, a SiO2 film, a SiN film,a SiON film, a Poly-Si film, or a SiCN film. The silicon-containing film33 may be formed of such a material that it functions as ananti-reflection film in a lithography process. When etching the organicfilm 32, the silicon-containing film 33 functions as a hard mask. Apredetermined pattern, which may be referred to as “opening”hereinafter, is formed in the silicon-containing film 33.

The method for processing a substrate according to one embodimentcontrols the shape of a pattern formed in the organic film 32 bycombining the following steps (1) to (4).

-   -   (1) Step for forming a protective film    -   (2) Step of etching    -   (3) Step for building up a mask    -   (4) Step for preventing clogging

Step for Forming a Protective Film

In the step for forming a protective film, a processing gas is turnedinto plasma, and the organic film 32 is etched while thesilicon-containing film 33 is sputtered. The products generated from thesputtering of the silicon-containing film 33 are deposited on a sidewall of a recess in the organic film 32 and form a protective film 40.The processing gas used in this step is one example of a firstprocessing gas, and the step for forming a protective film is oneexample of a first step.

FIG. 3 is a diagram for explaining the step for forming a protectivefilm according to one embodiment. The structure S shown in FIG. 2 hasbeen subjected to the step for forming a protective film. The processinggas used in this step contains, for example, hydrogen (H2). Theprocessing gas is turned into plasma, and the structure S is exposed tothe plasma. The silicon-containing film 33 is sputtered by being exposedto the plasma generated from H2, and sputtered products scatter and aredeposited on the side wall of the recess of the organic film 32. Thestructure S shown in FIG. 3 includes the protective film 40 deposited onthe side wall of the recess of the organic film 32 and thesilicon-containing film 33. In the step for forming a protective film,the formation of the protective film 40 by sputtering thesilicon-containing film 33 and the etching of the recess of the organicfilm 32 proceed simultaneously as the plasma is generated from theprocessing gas. The processing gas may contain H2 alone or may be amixed gas containing N2 (nitrogen) gas and H2 gas.

Step of Etching

FIG. 4 is a diagram for explaining the step of etching of the method forprocessing a substrate according to one embodiment. In the step ofetching, the processing gas is turned into plasma, and the organic film32 is etched in a depth direction using the silicon-containing film 33as a mask. The processing gas used in this step is one example of asecond processing gas. The step of etching is one example of a secondstep. The organic film 32 is etched using a mixed gas containing O2(oxygen) gas and carbonyl sulfide (COS) gas, for example. The processinggas may include Cl2 (chlorine), HBr (hydrogen bromide), or the like. Theprocessing gas is prepared so as to etch mainly the organic film 32.When the step of etching is performed on the organic film 32, thesilicon-containing film 33 serving as a hard mask is gradually removed,and a recess with a shape corresponding to the shape of the opening inthe silicon-containing film 33 is formed in the organic film 32, and therecess gradually becomes deeper.

Step for Building Up a Mask

In the step for building up a mask, the thickness of thesilicon-containing film 33 on the mask is increased by, for example,anisotropic formation of a film. The step for building up a mask is oneexample of a third step. FIGS. 5A and 5B are diagrams for explaining thestep for building up the mask according to one embodiment. As shown inFIG. 5A, the thickness of the silicon-containing film 33 has beengradually reduced in the step for forming a protective film and the stepof etching. When the pattern to be formed in the organic film 32 has ahigh aspect ratio, the silicon-containing film 33, i.e., a hard mask,may disappear before the bottom of the pattern reaches the insulatingfilm 31. To avoid this, a film is formed on the silicon-containing film33 using plasma of a third processing gas in the step for building up amask. The conditions for forming the film are set to be anisotropic.That is, the conditions are set such that a film is mainly formed on thetop of the silicon-containing film 33 while the opening is not clogged(see FIG. 5B).

The third processing gas used in the step for building up a mask may bea mixed gas containing a silicon halide gas such as SiCl4 or SiF4, arare gas such as argon (Ar), and O2. The third processing gas is turnedinto plasma, and the structure S is exposed to the plasma. Particulartechniques employed for forming a film in the step for building up amask is not limited. Such technique may include a chemical vapordeposition (CVD), a physical vapor deposition (PVD), an atomic layerdeposition (ALD), a direct current superposition (DCS) and others. Thecomposition of the film formed in the step for building up a mask doesnot need to be the same as that of the silicon-containing film 33. Thefilm formed in the step for building up a mask may be asilicon-containing film having a composition different from that of thesilicon-containing film 33. Further, the film formed in the step forbuilding up a mask may be of a material having a high selectivity withrespect to the organic film 32, and may not be a silicon-containingfilm.

Step for Preventing Clogging

FIGS. 6A and 6B are diagrams for explaining the step for preventingclogging according to one embodiment. The step for preventing cloggingremoves by a processing gas containing fluorine (F) deposits that mayclog the upper portion of the pattern and/or the opening. Such depositsmay be generated in any of the steps including the step for forming aprotective film, the step of etching, and the step for building up amask. The processing gas used in the step for preventing clogging is oneexample of a fourth processing gas. The step for preventing clogging isone example of a fourth step. As shown in FIG. 6A, while a pattern isformed in the structure S, products (D in (1) of FIG. 6A) may begenerated by etching and adhere to the side wall of the opening. Then,the opening may be gradually clogged. In addition, while the mask isbeing build up, products (D′ in (2) of FIG. 6A) may grow in a horizontaldirection, and gradually clog the upper portion of the pattern or theopening. In the step for preventing clogging, an excessive deposits(product) that may clog the opening or the pattern are removed by plasmagenerated from a fluorine-containing gas. When the products D or theproducts D′ are partially removed, the dimension of the opening of thesilicon-containing film 33 is recovered ((1) and (2) in FIG. 6B), andthe processing gas can be evenly delivered to the bottom of the patternin a subsequent step (e.g., step of etching). The processing gas used inthe step for preventing clogging may be, for example, a mixed gas of afluorine-containing gas such as CHF3 and CF4, and a rare gas such as N2gas or argon (Ar) gas.

Next, the method for processing a substrate according to one embodimentwill be described with reference to FIGS. 1 and 7A. FIG. 1 is aflowchart showing an exemplary flow of the method for processing asubstrate according to one embodiment. FIG. 7A is a diagram forexplaining an exemplary flow of FIG. 1.

First, the structure S is prepared (Step S100, (1) of FIG. 7A).Subsequently, it is determined whether or not the structure S satisfiesa condition A (Step S101). The condition A is, for example, that thethickness of the silicon-containing film 33 on the organic film 32 isequal to or greater than a predetermined value. In this embodiment, thestructure S generally satisfies the condition A (Step S101, Yes) whenthe step S101 is first performed, i.e., in a first cycle. Then, theprocess proceeds to Step S103 without performing the step for buildingup a mask. In the second and subsequent cycles, it may be determinedthat the structure S does not satisfy the condition A (Step S101, No).Then, the step for building up a mask is performed (Step S102).

In Step S103, it is determined whether or not the structure S satisfiesa condition B. The condition B is, for example, that the aspect ratio ofthe pattern formed on the organic film 32 reaches a predetermined valueα. For example, the predetermined value α is 5. Further, for example,the condition B is that the protective film 40 (see FIG. 3) is formed onthe patterned organic film 32.

When it is determined that the structure S does not satisfy thecondition B (Step S103, No), the step for forming a protective film isperformed (Step S104, (2) of FIG. 7A). For example, when no pattern isformed in the organic film 32, it is determined that the structure Sdoes not satisfy the condition B. Then, the step for forming aprotective film is performed. During this step, the organic film 32 isetched. Simultaneously, the silicon-containing film 33 is sputtered, andproducts generated by the sputtering are deposited on the side wall ofthe pattern (recess) formed in the organic film 32 and form theprotective film 40. When Step S104 finishes, the process returns to StepS101. At Step S101, when it is determined that the thickness of thesilicon-containing film 33 is reduced in the step for forming aprotective film and the structure S does not satisfy the condition A(Step S101, No), the step for building up a mask is performed (StepS102).

When it is determined that the structure S satisfies the condition B(Step S103, Yes), the process proceeds to Step S105. It is determinedthat the structure S satisfies the condition B, for example, when theaspect ratio of the pattern formed in the organic film 32 is 6. Further,it is determined that the structure S satisfies the condition B, forexample, when the aspect ratio of the pattern in the organic film 32reaches 5 as a result of performing the step for forming a protectivefilm several times. When it is determined that the structure S satisfiesthe condition B, the process proceeds to Step S105.

In one embodiment, once the structure S satisfies the condition B, theprotective film need not be formed in the subsequent steps. In thiscase, the determination in Step S103 is set such that once the processproceeds to Step S105, the determination in Step S103 may be always YES.However, when the protective film 40 is removed by repeatedly performingStep S106 and the structure S does not satisfy the condition B (StepS103, No), the step for forming a protective film may be performed (StepS104).

In Step S105, it is determined whether or not the structure S satisfiesa condition C. The condition C is, for example, that the dimension ofthe opening of the silicon-containing film 33 is equal to or greaterthan a predetermined dimension. When it is determined that the structureS does not satisfy the condition C (Step S105, No), the step forpreventing clogging is performed (Step S106). When Step S106 finishes,the process returns to Step S101. On the other hand, when it isdetermined that the structure S satisfies the condition C (Step S105,Yes), the process proceeds to Step S107.

In Step S107, it is determined whether or not the structure S satisfiesa condition D. The condition D is, for example, that the aspect ratio ofthe pattern formed in the organic film 32 is equal to or greater than apredetermined value β, different from the predetermined value α. Forexample, the predetermined value β, indicating an aspect ratio is 20 to30. When it is determined that the structure S does not satisfy thecondition D (Step S107, No), the step of etching is performed (StepS108, (3) of FIG. 7A). When Step S108 finishes, the process returns toStep S101. At this time, the thickness of the silicon-containing film 33may have been reduced due to Step S104 and Step S108, and thus it may bedetermined that the structure S does not satisfy the condition A (StepS101, No). Then, the step for building up a mask is performed (StepS102, (4) of FIG. 7A). Further, the size of the opening of thesilicon-containing film 33 may have been reduced due to Step S102 andStep S108, and then it may be determined that the structure S does notsatisfy the condition C (Step S106, No). In this case, the step forpreventing clogging is performed (Step S106, (5) of FIG. 7A).

When it is finally determined in Step S107 that the structure Ssatisfies the condition D (Step S107, Yes) by repeatedly performing theabove process, the process ends.

FIG. 7B is a diagram for explaining another exemplary flow of FIG. 1. In(1) of FIG. 7B, it is assumed that a large amount of thesilicon-containing film 33 of the structure S has been removed, but thefilm thickness is not less than a predetermined value of the condition A(Step S101, Yes). Further, it is assumed that the aspect ratio of thepattern of the mask is less than the predetermined value β (Step S107,No). Then, the step of etching is performed to etch the pattern of themask (Step S108). As a result of the etching, it is assumed that thesilicon-containing film 33 has been reduced and the film thickness isless than a predetermined value (Step S101, No). Then, the step forbuilding up a mask is performed to increase the height of the mask ((2)of FIG. 7B). When the structure S satisfies the conditions A to D, theprocess ends.

In this way, according to the method for processing a substrate shown inFIG. 1, the step to be performed is selected according to the state ofthe processed structure S. The step for forming a protective film, thestep of etching, the step for building up a mask, and the step forpreventing clogging are selectively performed by appropriately settingthe conditions A to D for determining whether or not to perform eachprocess step. Hence, the process suitable for the state of the structureS can be performed. The determination as to whether or not the structureS satisfies the conditions A to D may be made by setting in advance thenumber of times each step is to be performed until the conditions A to Dare satisfied. In addition, the processing condition of each step may beset in advance. For example, whether or not the conditions A to D aresatisfied may be determined based on the number of times each step hasbeen performed.

In the example shown in FIG. 1, each step is performed after thecorresponding determination is made based on the conditions A to D as towhether or not to perform the step for forming a protective film, thestep of etching, the step for building up a mask, and the step forpreventing clogging. However, the flow of the method for processing asubstrate according to the present embodiment is not limited to the flowshown in FIG. 1. A combination of steps may be selected in advance fromthe step for forming a protective film, the step of etching, the stepfor building up a mask, and the step for preventing clogging. Then, theorder and the number of times the selected steps are to be performed maybe set in advance. For example, a cycle including any of the step forforming a protective film, the step of etching, the step for building upa mask, and the step for preventing clogging may be determined inadvance, and each cycle may be performed a predetermined number oftimes.

FIG. 8 is a flowchart of exemplary cycle 1 of the method for processinga substrate according to one embodiment. Exemplary cycle 1 includes thestep for forming a protective film (Step S61) and the step for buildingup a mask (Step S62). In the exemplary cycle 1, first, the protectivefilm is formed on the side wall of the organic film 32 in the step forforming a protective film. Thereafter, the height of the hard mask (thesilicon-containing film 33) reduced by sputtering in the step forforming a protective film is recovered in the step for building up amask. In FIGS. 8 to 10, “Pre-C” indicates a previous cycle, and “Post-C”indicates a subsequent cycle.

FIG. 9 is a flowchart showing exemplary cycle 2 of the method forprocessing a substrate according to one embodiment. Exemplary cycle 2includes the step of etching (Step S71) and the step for preventingclogging (Step S72). In the exemplary cycle 2, first, the organic film32 is patterned by etching the organic film 32. Thereafter, the productsdeposited on the side wall of the opening or the side wall of the upperportion of the pattern in the etching step are removed in the step forpreventing clogging.

FIG. 10 is a flowchart showing exemplary cycle 3 of the method forprocessing a substrate according to one embodiment. Exemplary cycle 3includes the step for building up a mask (Step S81), the step of etching(Step S82), and the step for preventing clogging (Step S83). In theexemplary cycle 3, first, the reduced height of the hard mask (thesilicon-containing film 33) is recovered. Thereafter, the pattern of theorganic film 32 is etched in a depth direction. Then, the productdeposited on the side wall of the opening or the side wall of the upperportion of the pattern in the step of etching is removed.

The shape of the pattern can be controlled by combining the exemplarycycles 1 to 3 according to the depth of the pattern of the organic film32. For example, the exemplary cycle 1 may be performed before etching(where the organic film 32 has not been etched). Then, the protectivefilm may be formed by sputtering the silicon-containing film 33 whileetching the organic film 32, thus preventing the bowing of the organicfilm 32. Furthermore, the step for building up a mask can supplant thetop portion of the silicon-containing film 33 that has disappeared bysputtering. Subsequently, the exemplary cycle 2 may be performed afterthe organic film 32 is etched, for example, when the etched depthreaches a region where bowing is likely to occur. The region where thebowing is likely to occur, e.g., a region right below thesilicon-containing film 33 is covered by the protective film 40. Thus,the organic film 32 can be etched without causing a bowing. Furthermore,the products generated from the etching and deposited on the side wallof the opening and the side wall of the upper portion of the pattern canbe removed in the step for preventing clogging. Since the etching of theorganic film 32 also removes the hard mask, the exemplary cycle 3 may beperformed. In the exemplary cycle 3, the etching can be performed afterthe hard mask is built up. In addition, the clogging of the opening atthe top of the pattern can be prevented.

In this way, the cycles each including some of the step for forming aprotective film, the step of etching, the step for building up a mask,and the step for preventing clogging can be combined according to thestate of the pattern, e.g., the depth of the pattern, formed on thestructure S. Therefore, the shape of the pattern can be controlled.

FIG. 11 is a flowchart of an exemplary combination of cycles of themethod for processing a substrate according to one embodiment. In theexample shown in FIG. 11, firstly the exemplary cycle 1 is performed apredetermined number of times, for example, five times; then theexemplary cycle 2 is performed a predetermined number of times, forexample, three times; and the exemplary cycle 3 is performed apredetermined number of times, for example, four times. The processcondition of the exemplary cycle 3 is changed during the process. Forexample, the exemplary cycle 3 may be performed three times, and theprocess condition may be changed, and again the exemplary cycle 3 may beperformed once based on the changed process condition.

First, the exemplary cycle 1 is performed (Step S901). Then, it isdetermined whether the exemplary cycle 1 is performed a predeterminednumber of times (Step S902). When it is determined that the exemplarycycle 1 is not performed a predetermined number of times (Step S902,No), the process returns to Step S901, and the exemplary cycle 1 isrepeated. On the other hand, when it is determined that the exemplarycycle 1 is performed a predetermined number of times (Step S902, Yes),the process proceeds to Step S903, and the exemplary cycle 2 isperformed. Then, it is determined whether the exemplary cycle 2 isperformed a predetermined number of times (Step S904). When it isdetermined that the exemplary cycle 2 is not performed a predeterminednumber of times (Step S904, No), the process returns to Step S903, andthe exemplary cycle 2 is repeated. On the other hand, when it isdetermined that the exemplary cycle 2 is performed a predeterminednumber of times (Step S904, Yes), the process proceeds to Step S905, andthe exemplary cycle 3 is performed. Here, the exemplary cycle 3 at StepS905 is performed under a process condition 1. For example, under theprocess condition 1, the processing time of the step for building up amask may be set to 10 seconds. Subsequently, it is determined whetherthe exemplary cycle 3 based on the process condition 1 is performed apredetermined number of times (Step S906). When it is determined thatthe exemplary cycle 3 is not performed a predetermined number of times(Step S906, No), the process returns to Step S905, and the exemplarycycle 3 is repeated. On the other hand, when it is determined that theexemplary cycle 3 is performed a predetermined number of times (StepS906, Yes), the process proceeds to Step S907, and the exemplary cycle 3is performed. The exemplary cycle 3 at Step S907 is performed under aprocess condition 2. For example, under the process condition 2, theprocessing time of the step for building up a mask is set to 20 seconds.Then, it is determined whether the exemplary cycle 3 under the processcondition 2 is performed a predetermined number of times (Step S908).When it is determined that the exemplary cycle 3 is not performed apredetermined number of times (Step S908, No), the process returns toStep S907, and the exemplary cycle 3 is repeated. On the other hand,when it is determined that the exemplary cycle 3 is performed apredetermined number of times (Step S908, Yes), the process ends.

In this way, in the method for processing a substrate according to theembodiment, the steps to be performed and the processing conditions arechanged according to the processing state of the pattern formed on thestructure S, for example, how much the etching has been done. Further,the process according to the embodiment is simple because it consists ofrepeatedly performed cycles, each of which is a combination of steps.

Result of Experimentation

FIG. 12 is a view for explaining effects obtained by the method forprocessing a substrate according to one embodiment. In FIG. 12, (A)shows a state where the silicon-containing film 33, formed on theorganic film 32, is patterned (the depicted shape corresponds to thatshown in FIG. 2). In (A), the vertical dimensions of each of theinsulating film 31, the organic film 32, and the silicon-containing film33 are each indicated by a single-sided or double-sided arrow. Further,(B) shows a state (comparative example) of the structure of (A) afterthe step of etching is performed without the formation of the protectivefilm (40 in FIG. 3). Further, (C) shows a state (example) of thestructure of (A) after the organic film is patterned by the method forprocessing a substrate according to the embodiment.

The structures were formed to have the insulating film 31 (film to beetched), the organic film 32 (mask) formed on the insulating film 31,and the silicon-containing film 33 (hard mask) formed on the organicfilm 32. Thereafter, as shown in (A) of FIG. 12, an opening was formedin the silicon-containing film 33. In (A), the organic film 32 wasslightly removed due to the influence of the etching.

First, in the comparative example (B), a mixed gas of O2 gas and COS gaswas supplied into the chamber at a flow rate of 250/50, and the organicfilm 32 was etched through the silicon-containing film 33 as a hardmask. The pressure of the chamber was set to 20 mTorr, and the voltagesof the upper electrode and the lower electrode were set to 1400 W and500 W, respectively. Further, the frequencies of the upper electrode andthe lower electrode were set to 27 MHz and 13 MHz, respectively.Further, the temperatures (T/W/B) of the top, the side wall and thebottom of the chamber were set to 120° C., 100° C., and 10° C.,respectively. Further, the length of the step of etching was set to 300seconds and the step was performed once.

In the example (C), the exemplary cycles 1 to 3 were performed with thecombinations shown in FIG. 11. The order is as follows. First, theexemplary cycle 1 was performed five times, the exemplary cycle 2 wasperformed three times, and then the exemplary cycle 3 was performed fourtimes. In the first three of the exemplary cycles 3, the step forpreventing clogging was performed 10 seconds. In the last of theexemplary cycles 3, the step for building up a mask was performed for 20seconds.

The processing conditions of each of the step for forming a protectivefilm, the step of etching, the step of building up a mask, and the stepfor preventing clogging are as follows.

Step for Forming a Protective Film:

Chamber pressure: 20 mTorr

Voltage of upper electrode and lower electrode:

0 W+900 W

Flow rate of H2 gas: 250 sccm

Chamber temperature: T/W/B=120° C./100° C./10° C.

Processing time: 120 seconds

Step of Etching:

Chamber pressure: 20 mTorr

Flow rate of processing gas: O2/CO2=250 sccm/50 sccm

Chamber temperature: T/W/B=120° C./100° C./10° C.

Processing time: 100 seconds

Step for Building Up a Mask:

Chamber pressure: 20 mTorr

Voltage of upper electrode and lower electrode:

800 W+0 W

Flow rate of processing gas: Ar/O2/SiCl4=500 sccm/100 sccm/20 sccm

Chamber temperature: T/W/B=120° C./100° C./10° C.

Step for Preventing clogging:

Chamber pressure: 30 mTorr

Voltage of upper electrode and lower electrode:

300 W+140 W

Flow rate of processing gas: CHF3/CF4/N2=300 sccm/100 sccm/150 sccm

Chamber temperature: T/W/B=120° C./100° C./10° C.

Processing time: 30 seconds

A structure shown in (B) of FIG. 12 was obtained by the processing ofthe comparative example. As can be seen from (B) of FIG. 12, in thecomparative example, bowing has occurred in the upper portion of theorganic film 32 (a portion indicated by a dotted rectangle). Thus, thepattern formed in the organic film 32 is generally tapered from the topto the bottom, and the dimension of the opening is slightly narrowed atthe bottom of the pattern (about 78 nm). The vertical dimension of thepattern is about 2500 nm.

In contrast, in the example ((C) of FIG. 12), first, the protective film40 was formed by the exemplary cycle 1, and the pattern shown on theleft side of (C) was formed in the upper portion of the organic film 32(see the figure on the left side of (C) of FIG. 12). After the aspectratio reached approximately 5, the exemplary cycles 2 and 3 wereperformed to complete the pattern of the organic film 32 (see the figureon the right side of (C) of FIG. 12).

As can be seen from (C) of FIG. 12, in the example, bowing hardly occursin the upper portion of the organic film 32. Therefore, the spread inthe lateral direction is significantly reduced as compared with thecomparative example (a portion indicated by a dotted rectangle).Specifically, the lateral dimension of the bowing, which was about 170nm in the comparative example, was improved to about 105 nm in theexample. Further, the taper from the top to the bottom of the patternformed on the organic film 32 is generally reduced, and the dimension ofthe opening at the bottom of the pattern is improved as compared withthe comparative example (about 87 nm).

In the step for forming a protective film in the above embodiment,hydrogen (H2) gas was used as the processing gas. However, theprocessing gas other than hydrogen gas can be used as the processing gasin the step for forming a protective film, as long as the rate offormation of the protective film is higher than the rate of bowingformation during the etching.

Region where a Protective Film is to be Formed

The inventors also studied conditions used for determining whether ornot to perform the step for forming a protective film. FIG. 13 is a viewfor explaining conditions used when determining whether or not toperform the step for forming a protective film in the method forprocessing a substrate according to one embodiment. By referring to FIG.13, the condition B used for determining whether or not to perform thestep for forming a protective film will be described.

Six patterns (A) to (F) shown in FIG. 13 respectively show examples ofthe following states.

(A) State 1: immediately after a pattern is formed on thesilicon-containing film 33 of the structure S

(B) State 2: after the step for forming a protective film is performedfor 30 seconds on the pattern of State 1

(C) State 3: after the step of etching is performed for 300 seconds onthe pattern of State 2

(D) State 4: after the step for forming a protective film is performedfor 120 seconds on the pattern of State 1

(E) State 5: after the step of etching is performed for 300 seconds onthe pattern of State 4

(F) State 6: after the step for forming a protective film is performedfor 600 seconds on the pattern of State 1

In the example of FIG. 13, the processing conditions of the step forforming a protective film and the step of etching are as follows.

Step for Forming a Protective Film:

Chamber pressure: 20 mTorr

Voltage of upper electrode and lower electrode:

0 W+900 W

Flow rate of processing gas: H2=250

Chamber temperature: T/W/B=120° C./100° C./10° C.

Step of Etching:

Chamber pressure: 20 mTorr

Voltage of upper electrode and lower electrode: 1400 W+500 W

Flow rate of processing gas: O2/CO2=250 sccm/50 sccm

Chamber temperature: T/W/B=120° C./100° C./10° C.

In State 1 shown in (A) of FIG. 13, an opening tapered from the top tothe bottom is formed in the silicon-containing film 33 of the structureS. Thickness of the silicon-containing film 33 shown in the example ofFIG. 13 is about 215 nm. When the step for forming a protective film isperformed on the structure S under the above processing conditions for30 seconds, as shown in (B), the organic film 32 is etched, and theprotective film 40 is formed on the side wall of the opening formed bythe etching.

When the step of etching is performed on the structure S in State 2 for300 seconds, bowing that expands laterally occurs in the opening in theorganic film 32 from immediately below the organic film 32, and aportion of the organic film 32 is removed to form the shape shown in(C). In State 3, the opening formed in the organic film 32 has no bowingat the position where the protective film 40 is formed (the positionindicated by A1 in FIG. 13). Bowing occurs from immediately below theprotective film 40.

When the processing time of the step for forming a protective film isextended from 30 seconds to 120 seconds, the depth of the opening formedon the organic film 32 increases, and accordingly, the region where theprotective film 40 is formed extends in the depth direction ((D) of FIG.13). In State 4 shown in (D), the protective film 40 is formed to adepth of about 130 nm from the top of the organic film 32 (see a portionindicated by A2 in FIG. 13). When the etching step is performed on thestructure S in State 4 under the above processing conditions for 300seconds, as shown in (E), the position where bowing occurs moves lowerthan that of the example of (C), and the amount of bowing decreases.Thus, it can be seen that the position and amount of bowing can becontrolled by forming the protective film 40. However, in the example of(E), as a result of the step of etching, the silicon-containing film 33serving as a mask is removed, and the opening is clogged by deposits onthe top.

Further, as shown in (F), when the step for forming a protective film isperformed on the structure S in State 1 under the above processingconditions for 600 seconds, the protective film 40 formed on the organicfilm 32 reaches a depth of about 380 nm in the opening. As theprocessing time of the step for forming a protective film becomeslonger, the amount of the silicon-containing film 33 that is removed(etched) also increases. In the example shown in (F), a portion of themask of the silicon-containing film 33 is removed in a thicknessdirection, and the mask is distorted in shape and has a rough surface.

Thus, when the aspect ratio of the pattern formed in the organic film 32is higher, the problems such as the loss of the mask and the clogging ofthe opening in the silicon-containing film 33 occur when the step forforming a protective film and the step of etching are simply repeated.On the other hand, as a result of the above experiments, the presentinventors have found that bowing can be effectively reduced by formingthe protective film on the upper portion of the opening when the patternformed in the organic film 32 has a diameter of about 100 nm and a depthof about 2000 to 3000 nm. For example, for an opening with a diameter of100 nm, bowing was significantly reduced by forming the protective film40 on a region of about 500 nm from the top. Further, bowing wassignificantly reduced by forming the protective film 40 on a regionhaving an aspect ratio of about 6.7. From these, the inventors concludedthat the shape of the pattern could be improved by forming theprotective film 40 on a region having an aspect ratio of about 5 to 7.

Exemplary Apparatus for Processing a Substrate

FIG. 14 is a sectional view of a schematic configuration of a substrateprocessing apparatus 100 according to one embodiment. The substrateprocessing apparatus 100 includes a processing chamber (chamber) 102formed of a metal (e.g., aluminum) in a tubular shape (e.g., cylindricalshape).

A substrate support 110 for placing substrate is provided on the bottomof the processing chamber 102. The substrate support 110 has asubstantially columnar shape (e.g., cylindrical shape) made of aluminumor other metal. The substrate support 110 may have various functions asrequired, such as an electrostatic chuck, and a temperature controlmechanism such as a heater and a coolant channel. In an etchingapparatus, a bias radio-frequency power for drawing ions into thesubstrate W is supplied to the substrate support 110.

A plate-like dielectric 104 made of, for example, quartz glass, ceramic,or other material is provided on the ceiling of the processing chamber102 to face the substrate support 110. Specifically, the plate-likedielectric 104 is formed, for example, in a disc shape, and ishermetically attached to close an opening formed in the ceiling of theprocessing chamber 102.

The processing chamber 102 is provided with a gas supply unit 120 thatsupplies a processing gas, or other gases. A gas inlet 121 is formed ina side wall of the processing chamber 102. A gas supply source 122 isconnected to the gas inlet 121 via a gas supply line 123. A flowcontroller for controlling the flow rate of the processing gas, forexample, a mass flow controller (MFC) 124 and an opening and closingvalve 126 are arranged in the gas supply line 123. According to this gassupply unit 120, the processing gas from the gas supply source 122 iscontrolled to a predetermined flow rate by the mass flow controller 124and is supplied from the gas inlet 121 into the processing chamber 102.

For simplicity of explanation, in FIG. 14, the gas supply unit 120 isrepresented as a single line system. However, the gas supply unit 120 isnot limited to one supplying the processing gas of one type. The gassupply unit 120 may supply more than one type of the processing gas. Inthis case, a plurality of gas supply sources may be provided andconfigured with a plurality of gas supply lines, and each gas supplyline may be provided with a mass flow controller. FIG. 14 shows anexample where the gas supply unit 120 is configured to supply gas fromthe side wall of the processing chamber 102, but the disclosure is notnecessarily limited to this. For example, gas may be supplied from theceiling of the processing chamber 102. In this case, for example, a gasinlet may be formed at, for example, the center of the plate-likedielectric 104, and gas may be supplied from the gas inlet.

As the processing gas supplied into the processing chamber 102 by thegas supply unit 120, a halogen-based gas containing Cl, F or the like isused for etching an oxide film, for example. Specifically, when etchinga silicon oxide film such as SiO2 film, a fluorocarbon gas such as CxFy,CHF3 gas is used as the processing gas.

An exhaust unit 130 for exhausting the atmosphere in the processingchamber 102 is connected to the bottom of the processing chamber 102 viaan exhaust line 132. The exhaust unit 130 is configured by, for example,a vacuum pump, and can reduce the pressure in the processing chamber 102to a predetermined pressure. A substrate loading/unloading port 134 isprovided in the side wall of the processing chamber 102. The substrateloading/unloading port 134 is provided with a gate valve 136. Forexample, when loading the substrate W, the gate valve 136 is opened, andthe substrate W is placed on the substrate support 110 in the processingchamber 102 by a transfer mechanism such as a transfer arm (not shown).Then, the gate valve 136 is closed, and the substrate W is processed.

On the ceiling of the processing chamber 102, a planar radio-frequencyantenna 140 and a shield member 160 for covering the antenna 140 arearranged on an upper surface (outer surface) of the plate-likedielectric 104. The radio-frequency antenna 140 in the presentembodiment is roughly configured by an inner antenna element 142Aarranged at the center of the plate-like dielectric 104 and an outerantenna element 142B arranged to surround the outer periphery of theinner antenna element 142A. Each of the antenna elements 142A, 142B isformed in a spiral coil shape made of, for example, a conductor such ascopper, aluminum, and stainless steel.

The shield member 160 in the present embodiment includes a tubular innershield wall 162A provided between the antenna elements 142A, 142B so asto surround the inner antenna element 142A, and a tubular outer shieldwall 162B provided so as to surround the outer antenna element 142B. Theupper surface of the plate-like dielectric 104 is divided into a centralportion (central zone) inside the inner shield wall 162A and aperipheral portion (peripheral zone) between the shield walls 162A,162B.

A disc-shaped inner shield plate 164A for closing an opening of theinner shield wall 162A is provided over the inner antenna element 142A.A donut-shaped outer shield plate 164B for closing an opening betweenthe shield walls 162A, 162B is provided over the outer antenna element142B.

The shape of the shield member 160 is not limited to a cylindricalshape. Although the shield member 160 may have other shapes such as arectangular tube shape, it is desirable to match it with the shape ofthe processing chamber 102. Here, for example, the processing chamber102 is formed in a substantially cylindrical shape, and accordingly, theshield member 160 is also formed in a substantially cylindrical shape.

Radio-frequency power supplies 150A, 150B are separately coupled to theantenna elements 142A, 142B, respectively. Thereby, a radio-frequencywith the same frequency or different frequencies may be supplied to eachof the antenna elements 142A, 142B. For example, when a radio-frequencywith a predetermined frequency (e.g., 40 MHz) is supplied at apredetermined power from the radio-frequency power supply 150A to theinner antenna element 142A, an induction magnetic field is formed in theprocessing chamber 102. The processing gas introduced into theprocessing chamber 102 is excited by the induction magnetic field, anddonut-shaped plasma is generated at the center above the substrate W.

When a radio-frequency with a predetermined frequency (e.g., 60 MHz) issupplied at a predetermined power from the radio-frequency power supply150B to the outer antenna element 142B, an induction magnetic field isformed in the processing chamber 102. The processing gas introduced intothe processing chamber 102 is excited by the formed induction magneticfield, and another donut-shaped plasma is generated at the periphery onthe substrate W.

A predetermined plasma process on the substrate, such as asking,etching, and deposition is performed by the above plasma. Theradio-frequency output from each of the radio-frequency power supplies150A, 150B is not limited to the above-described frequency. For example,a radio-frequency with various frequencies such as 13.56 MHz, 27 MHz, 40MHz, and 60 MHz can be supplied. However, it is necessary to adjust theelectrical length of each of the antenna elements 142A, 142B accordingto the radio-frequency output from the radio-frequency power supplies150A, 150B.

A controller (overall control device) 200 is connected to the substrateprocessing apparatus 100. Each unit of the substrate processingapparatus 100 is controlled by the controller 200. Further, thecontroller 200 is connected with an operation unit 210 that includes akeyboard for allowing an operator to input commands so as to manage thesubstrate processing apparatus 100, and a display for visualizing anddisplaying the operation status of the substrate processing apparatus100, and the like.

Furthermore, the controller 200 is connected with a storage unit 220that stores a program for realizing various processes performed by thesubstrate processing apparatus 100 under the control of the controller200, and recipe data necessary for performing the program, and the like.

For example, the storage unit 220 stores a recipe or the like forperforming a process such as cleaning in the processing chamber 102, inaddition to a plurality of process recipes for performing the processingon the substrate W. These recipes are obtained by collecting a pluralityof parameter values such as control parameters for controlling each unitof the substrate processing apparatus 100 and setting parameters. Forexample, the process recipe has parameter values such as a flow ratio ofthe processing gas, a pressure in the processing chamber 102, and afrequency and power of a radio-frequency applied to each of the antennaelements 142A, 142B.

These recipes may be stored in a hard disk or a semiconductor memory.Alternatively the recipes may be stored in a portable computer-readablestorage medium such as a CD-ROM or a DVD. These medium may be set in apredetermined position of the storage unit 220.

The controller 200 realizes a desired process in the substrateprocessing apparatus 100 by reading a desired process recipe from thestorage unit 220 based on instructions or the like from the operationunit 210 and controlling each unit of the substrate processing apparatus100. The recipe can be edited via the operation unit 210.

Meanwhile, although, in this embodiment, an Inductively Coupled Plasma(ICP) apparatus is illustrated as an example, the substrate processingapparatus 100 may be a Capacitively Coupled Plasma (CCP) apparatus.Further, in addition to the radio-frequency antenna 140 provided on theceiling of the processing chamber 102, a radio-frequency power may besupplied to a lower electrode included in the substrate support 110 togenerate plasma.

Advantageous Effect

The substrate processing method according to the above embodimentincludes providing a substrate having a first film and a second film onthe first film and having an opening formed in the second film andturning a first processing gas into plasma to etch the first film and toform a protective film on a sidewall of the first film by sputtering ofthe second film. In the substrate processing method according to theembodiment, the formation of the protective film by the sputtering ofthe second film and the etching of the first film can be performed inparallel. Therefore, according to the embodiment, the first film can beetched while reducing the bowing of the first film (organic film).Further, according to the substrate processing method of the embodiment,the protective film can be formed at a position where bowing is likelyto occur, so that bowing can be effectively suppressed. The first stepmay be performed, for example, until an aspect ratio of a pattern formedon the first film becomes at least 5.

Further, the substrate processing method according to the embodiment mayfurther include a second step of turning a second processing gas intoplasma and etching the first film through the second film.

Further, the substrate processing method according to the embodiment mayfurther include a third step of turning a third processing gas intoplasma and forming a silicon-containing film at the top of the secondfilm. Therefore, according to the embodiment, the etching can becontinued by increasing a film on the second film by the third step whenthe amount of the second film functioning as a mask is reduced.Therefore, according to the embodiment, a pattern having a high aspectratio can be formed on the first film.

Further, the substrate processing method according to the embodiment mayfurther include a fourth step of turning a fourth processing gas intoplasma and removing what clogs an upper portion of a pattern and/or anopening generated in any one of the first step, the second step and thethird step. Therefore, according to the embodiment, the etching can beperformed while reducing the clogging of the opening by appropriatelypreforming the fourth step when there is a possibility that the openingor the upper portion of the pattern is clogged by a deposition.

Further, in the substrate processing method according to the embodiment,a plurality of cycles in which one or more steps including at least oneof the second step, the third step or the fourth step are combined maybe performed in a predetermined order and a predetermined number oftimes. Therefore, according to the embodiment, the shape formed byetching can be controlled by performing a process suitable for thedegree of progress of the etching.

Further, in the substrate processing method according to the embodiment,a pattern having an aspect ratio of 20 or more may be formed on thefirst film.

Further, in the substrate processing method according to the embodiment,the first processing gas that is a hydrogen-containing gas may be turnedinto plasma, and the second film that is an anti-reflection film may besputtered.

Further, the substrate processing method according to the embodiment mayfurther include a step of etching an alternately stacked portion of asilicon oxide film and a silicon oxynitride film via the first film.

Further, the substrate processing apparatus according to the embodimentincludes a storage unit configured to store a program for performing thesubstrate processing method, and a controller for controlling theprogram to be performed. Therefore, according to the embodiment, theshape of the pattern formed on the substrate by etching can becontrolled.

The embodiments described in this disclosure are examples in allrespects, and should be considered not to be restrictive. Theembodiments may be omitted, replaced or changed in various forms withoutdeparting from the scope of the appended claims and the spirit thereof.

What is claimed is:
 1. A method of processing a substrate, comprising:(a) providing the substrate having a first film and a second film on thefirst film, and having an opening formed in the second film; and (b)etching the first film with a plasma generated from a first processinggas, the etching including forming a protective film on a sidewall ofthe first film by sputtering of the second film.
 2. The method accordingto claim 1, wherein the etching includes continuing the etching until anaspect ratio of a pattern formed in the first film is at least
 5. 3. Themethod according to claim 1, further comprising: (c) etching the firstfilm through the opening in the second film with a plasma generated froma second processing gas.
 4. The method according to claim 1, furthercomprising: (d) forming a silicon-containing film at a top of the secondfilm with a plasma generated from a third processing gas.
 5. The methodaccording to claim 1, further comprising: (e) removing an excessivedeposition that clogs an upper portion of a pattern formed in the firstfilm and/or the opening with a plasma generated from a fourth processinggas.
 6. The method according to claim 1, further comprising: (c) etchingthe first film through the opening in the second film with a plasmagenerated from a second processing gas; (d) forming a silicon-containingfilm at a top of the second film with a plasma generated from a thirdprocessing gas; and (e) removing an excessive deposition that clogs anupper portion of a pattern formed on the first film and/or the openingwith a plasma generated from a fourth processing gas, wherein one ormore cycles each including at least one step selected from the groupconsisting of (c), (d), and (e) are performed in order and for apredetermined number of times.
 7. The method according to claim 6,wherein the one or more cycles provides the first film with a patternhaving an aspect ratio of 20 or more.
 8. The method according to claim1, wherein the first processing gas includes a hydrogen-containing gas,and the second film being an anti-reflection film.
 9. The methodaccording to claim 1, further comprising: etching, after (b), a portionbelow the first film where a silicon oxide layer and a silicon nitridelayer are alternately arranged, or a portion where a silicon oxide layerand a polycrystalline silicon layer are alternately arranged, or aportion where a silicon oxide layer and a silicon oxynitride layer arealternately arranged.
 10. An apparatus for processing a substrate, theapparatus comprising: a chamber having a gas inlet and a gas outlet; aplasma generator; and a controller configured to (a) move a substrateinto the chamber, the substrate having a first film and a second film onthe first film and having an opening formed in the second film; and (b)control the plasma generator to generate a plasma from a firstprocessing gas into plasma so as to etch the first film, and sputter thesecond film to form a protective film on a sidewall of the first film.11. The apparatus according to claim 10, wherein the controller isfurther configured to control the plasma generator to continue an etchof the first film until an aspect ratio of a pattern formed in the firstfilm is at least
 5. 12. The apparatus according to claim 10, wherein thecontroller is further configured to: (c) etch the first film through theopening in the second film with a plasma generated from a secondprocessing gas.
 13. The apparatus according to claim 10, wherein thecontroller is further configured to: (d) control the plasma generator togenerate a plasma from a third processing gas to form asilicon-containing film at a top of the second film.
 14. The apparatusaccording to claim 10, wherein the controller is further configured to:(e) control the plasma generator to generate a plasma from a thirdprocessing gas to remove an excessive deposition that clogs an upperportion of a pattern formed in the first film and/or the opening. 15.The apparatus according to claim 10, wherein the controller is furtherconfigured to: (c) etch the first film through the opening in the secondfilm with a plasma generated from a second processing gas; (d) controlthe plasma generator to generate a plasma from a third processing gas toform a silicon-containing film at a top of the second film; and (e)control the plasma generator to generate a plasma from a thirdprocessing gas to remove an excessive deposition that clogs an upperportion of a pattern formed in the first film and/or the opening,wherein the controller is further configured to control one or morecycles each including at least one operation selected from the groupconsisting of (c), (d), and (e), and the one or more cycles areperformed in order and for a predetermined number of times.
 16. Theapparatus according to claim 15, wherein the controller is furtherconfigured to: perform the one or more cycles until a pattern in thefirst film is formed with an aspect ratio of 20 or more.
 17. Theapparatus according to claim 10, wherein the first processing gasincludes a hydrogen-containing gas, and the second film being ananti-reflection film.
 18. The apparatus according to claim 10, whereinthe controller is further configured to: control the plasma generator,after (b), to etch a portion below the first film where a silicon oxidelayer and a silicon nitride layer are alternately arranged, or a portionwhere a silicon oxide layer and a polycrystalline silicon layer arealternately arranged, or a portion where a silicon oxide layer and asilicon oxynitride layer are alternately arranged.